Congenital complete afibrinogenemia is a rare autosomal recessive disorder. The absence of fibrinogen makes blood incoagulable. The investigator is attempting to characterize the molecular defect in this disease. Total genomic DNA will be purified out of blood leukocytes. Probes for the 3 fibrinogen genes will be synthesized by RT-PCR using total liver RNA as the template and specific primers for the 3 chains that form fibrinogen dimers. The amplified cDNA is then labelled with P32. Southern blots will be performed in the Core Laboratory to look for gross deletions in one of the 3 genes. the lab will be utilized for oligonucleotide synthesis, PCR and Southern analysis.